Systems and methods for calibrating a tool

ABSTRACT

A calibration system includes a housing, a drive shaft within the housing, a load application apparatus operatively connected to the drive shaft to apply a force to the drive shaft, and a plurality of housing transducers operatively connected to the drive shaft to measure at least one of an in-line torque or a prevailing torque of the drive shaft. A method for calibrating a tool includes generating at least one of a pass or fail output from a processing unit based on whether a variance between a prevailing torque from a tool transducer and a prevailing torque from an external tool is within a predetermined variance threshold. A method for measuring prevailing torque in a tool includes determining whether a prevailing torque value is within a predetermined prevailing torque range and adjusting a shut-off threshold torque based on the prevailing torque.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.15/670,751, filed on Aug. 7, 2017, which claims priority to U.S.Provisional Patent Application No. 62/372,568 filed Aug. 9, 2016. Thecontents of U.S. patent application Ser. No. 15/670,751 and U.S.Provisional Patent Application No. 62/372,568 are incorporated byreference herein in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to tools, in particular to tools such astorque wrenches.

2. Description of Related Art

Present calibration methods for hand tools, such as torque wrenches,assume that the calibration with respect to the overall torque of thetool also calibrates with respect to prevailing torque. There is nocurrent method to measure prevailing torque at a given value and thencalibrate an automatic torque tool to that given value to ensure theautomatic torque tool is providing correct data. Moreover, traditionalsoftware for the tool, e.g. the torque wrench, provides only target andfinal torque values and does not currently provide a prevailing torquemeasurement.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for systems and methods that allow for improved calibrationof torque wrenches. The present invention provides a solution for theseproblems.

SUMMARY OF THE INVENTION

A calibration system includes a housing and a drive shaft within thehousing. The drive shaft extends to a connection point on a wall of thehousing. The calibration system includes a load application apparatusoperatively connected to the drive shaft to apply a force to the driveshaft. The calibration system includes a plurality of housingtransducers operatively connected to the drive shaft to measure at leastone of an in-line torque or a prevailing torque of the drive shaft.

In accordance with some embodiments, the calibration system includes aprocessing unit operatively connected to at least one of the pluralityof housing transducers to provide a pass/fail output. The pass/failoutput can be based on a comparison between the prevailing torquemeasurement from at least one of the housing transducers and aprevailing torque measurement from an external tool. It is contemplatedthat in certain embodiments, the calibration system includes aselectively removable tool operatively connected to the connection pointon the wall of the housing to apply a torque to the drive shaft. Theselectively removable tool can include a tool transducer to determine atleast one of an in-line torque and a prevailing torque being applied tothe drive shaft by the selectively removable tool.

The tool transducer can be operatively connected to a processing unitthat is operatively connected to at least one of the plurality ofhousing transducers. The processing unit can provide a pass/fail outputbased on a comparison between the prevailing torque measurement from atleast one of the plurality of housing transducers and the prevailingtorque measurement from the tool transducer.

In accordance with another aspect, a method for calibrating a toolincludes applying a torque to a drive shaft within a test-cart housingwith a load application apparatus. The method includes connecting aselectively removable tool to the drive shaft through a connection pointon a wall of the test-cart housing to apply a torque to the drive shaft,and determining the prevailing torque being applied to the drive shaftby the selectively removable tool with a tool transducer operativelyconnected to the selectively removable tool. The method includesdetermining the prevailing torque being applied to the drive shaft bythe load application apparatus with a test transducer operativelyconnected to the drive shaft.

The method includes comparing the prevailing torque being applied by theselectively removable tool to the prevailing torque being applied by theload application apparatus using a processing unit operatively connectedto at least one of the test transducer or the tool transducer todetermine a variance between the prevailing torque being applied by theselectively removable tool and the prevailing torque being applied bythe load application apparatus. The method includes generating at leastone of a pass or fail output from the processing unit based on whetherthe variance is within a predetermined variance threshold. It iscontemplated that in some embodiments, the method can includecalibrating the selectively removable tool if a fail output isgenerated.

In accordance with another aspect, a method for measuring prevailingtorque in a tool includes applying torque using a tool until a triggertorque threshold value is met in a torque transducer, and measuringtorque data recorded by the torque transducer until the trigger torquethreshold value is met. The method includes evaluating torque datarecorded by the torque transducer during applying the torque prior tothe trigger torque threshold value to determine a prevailing torquevalue, and determining whether the prevailing torque value is within apredetermined prevailing torque range. The method includes signaling atleast one of pass or fail depending on whether the prevailing torque iswithin the prevailing torque range. The method includes adjusting ashut-off threshold torque based on the prevailing torque.

The method can include shutting off the tool if fail is signaled. Themethod can include applying additional torque using the tool until theshut-off threshold torque is met if pass is signaled. In accordance withsome embodiments, the method includes adjusting at least one of aminimum shut-off torque or a maximum shut-off torque. Evaluating thetorque data recorded by the torque transducer during applying the torquecan include evaluating the torque data over a predetermined torqueevaluation angle range.

These and other features of the systems and methods of the subjectinvention will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject inventionappertains will readily understand how to make and use the devices andmethods of the subject invention without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1 is a schematic depiction of an exemplary embodiment of acalibration system constructed in accordance with an embodiment of thepresent disclosure;

FIG. 2 is a flow chart schematically depicting a method for calibratinga tool in accordance with an embodiment of the present disclosure;

FIG. 3 is a flow chart schematically depicting a method for measuringprevailing torque in a tool in accordance with an embodiment of thepresent disclosure; and

FIG. 4 is a schematic depiction of a plot of torque versus anglerecorded by a transducer showing the predetermined torque evaluationangle range in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, a schematic depiction of an exemplary embodiment of acalibration system constructed in accordance with the disclosure isshown in FIG. 1 and is designated generally by reference character 100.Other embodiments of calibration systems, methods for calibrating atool, and/or methods for measuring prevailing torque in a tool inaccordance with the disclosure, or aspects thereof, are provided inFIGS. 2-4, as will be described.

As shown in FIG. 1, a calibration system 100 includes a housing 102 anda drive shaft 104 within housing 102. Calibration system 100 is adynamic calibration system. Drive shaft 104 extends to a connectionpoint 106 on a wall 108 of housing 102. Calibration system 100 includesa load application apparatus 110 operatively connected to drive shaft104 to apply a force to drive shaft 104, e.g. a rotational force.Calibration system 100 includes a plurality of housing transducers 112and 114 operatively connected to drive shaft 104 to measure at least oneof an in-line torque or a prevailing torque of drive shaft 104.

With continued reference to FIG. 1, calibration system 100 includes aprocessing unit 116 operatively connected to at least one of housingtransducers 112 and 114 to provide a pass or fail output. Transducers112 and 114 can be wirelessly connected, hard-wired, or the like toprocessing unit 116 and/or drive shaft 104. The pass or fail output isbased on a comparison between the prevailing torque measurement from atleast one of housing transducers 112 and 114 and a prevailing torquemeasurement from an external tool 118. It is contemplated that incertain embodiments, calibration system 100 includes a selectivelyremovable tool 118 operatively connected to connection point 106 on wall108 of housing 102 to apply a torque to drive shaft 104. Selectivelyremovable tool 118 can be an automatic torque wrench or the like.

As shown in FIG. 1, selectively removable tool 118 includes a tooltransducer 120 to determine at least one of an in-line torque and aprevailing torque being applied to drive shaft 104 by selectivelyremovable tool 118. Tool transducer 120 is operatively connected toprocessing unit 116. Tool transducer 120 can be wirelessly connected,hard-wired, or the like, to processing unit 116. Processing unit 116provides one of a pass or fail output based on a comparison between theprevailing torque measurement from at least one of housing transducers112 and 114 and the prevailing torque measurement from tool transducer120.

As shown in FIG. 2, a method 200 for calibrating a tool, e.g. tool 118,includes applying a torque to a drive shaft, e.g. drive shaft 104,within a test-cart housing, e.g. housing 102, with a load applicationapparatus, e.g. load application apparatus 110, indicated schematicallyby box 202. Method 200 includes connecting the tool to the drive shaftthrough a connection point, e.g. connection point 106, on a wall of thetest-cart housing to apply a torque to the drive shaft, indicatedschematically by box 204. Method 200 includes determining the prevailingtorque being applied to the drive shaft by the tool with a tooltransducer, e.g. tool transducer 120, operatively connected to theselectively removable tool, indicated schematically by box 206. Methodincludes determining the prevailing torque being applied to the driveshaft by the load application apparatus with a test transducer, e.g. oneof housing transducers 112 and 114, operatively connected to the driveshaft, indicated schematically by box 208. Prevailing torque beingapplied to the drive shaft determined with either the test transducer orthe tool transducer can be determined using method 300, described below.

With continued reference to FIG. 2, method 200 includes comparing theprevailing torque being applied to the drive shaft by the selectivelyremovable tool to the prevailing torque being applied to the drive shaftby the load application apparatus using a processing unit, e.g.processing unit 116, operatively connected to at least one of the testtransducer or the tool transducer to determine a variance between theprevailing torque being applied by the selectively removable tool andthe prevailing torque being applied by the load application apparatus,indicated schematically by box 210. Method 200 includes generating atleast one of a pass or fail output from the processing unit based onwhether the variance is within a predetermined variance threshold,indicated schematically by box 212. The predetermined variance thresholdis a predetermined value stored in a database and selected based on thecharacteristics of pieces being joined together, e.g. the stack-up. Theinput of the predetermined variance threshold is indicated schematicallyby box 211. Method 200 includes calibrating the selectively removabletool if a fail output is generated, indicated schematically by box 214.

As shown in FIG. 3, a method 300 for measuring prevailing torque in atool, e.g. tool 118, includes applying torque to a fastener, forexample, using the tool until a trigger torque threshold value is met ina torque transducer, e.g. tool transducer 120, indicated schematicallyby box 302. Method 300 includes measuring torque data recorded by thetorque transducer until the trigger torque threshold value is met,indicated schematically by box 304. The trigger torque threshold valueis a predetermined value stored in a database and selected based on thestack-up. The input of the trigger torque threshold is indicatedschematically by box 303. Method 300 includes evaluating torque datarecorded by the torque transducer during applying the torque prior tomeeting the trigger torque threshold value to determine a prevailingtorque value, indicated schematically by box 306. Evaluating the torquedata recorded by the torque transducer during applying the torqueincludes evaluating the torque data over a predetermined prevailingtorque evaluation angle range. The prevailing torque evaluation anglerange is a predetermined value stored in a database and selected basedon the stack-up. The input of the predetermined prevailing torqueevaluation angle range is indicated schematically by box 305. This inputalso includes a predetermined angle offset, e.g. the amount of angle tolook back from the trigger torque threshold value to get to the top endof the predetermined prevailing torque evaluation angle range, as shownin more detail in FIG. 4. This predetermined angle offset can also bebased on the characteristics of the stack up.

With continued reference to FIG. 3, method 300 includes determiningwhether the prevailing torque value is within a predetermined prevailingtorque range, indicated schematically by box 308. The prevailing torquerange is a predetermined value stored in a database and selected basedon the stack-up. The input of the prevailing torque range is indicatedschematically by box 309. Method 300 includes signaling at least one of“pass” or “fail” depending on whether the prevailing torque is withinthe prevailing torque range, indicated schematically by box 310. If“fail” is signaled, method 300 includes shutting off the tool, indicatedschematically by box 312. If “pass” is signaled, method 300 includesapplying additional torque using the tool until a shut-off threshold ismet, indicated schematically by box 314. The shut-off threshold is apredetermined value stored in a database and selected based on thestack-up. The input of the shut-off threshold is indicated schematicallyby box 313. Method 300 includes adjusting the shut-off threshold basedon the prevailing torque, indicated schematically by box 316. Method 300includes adjusting minimum and maximum shut-off torques based on theprevailing torque, indicated schematically by 318.

Method 300 provides a more consistent prevailing torque measurement tobe used in compensating for the shut-off threshold, as compared withtraditional systems that use angle rotation data to identify prevailingtorque data, as the angle rotation data is not always repeatable andthus can result in different readings. Method 300 can be used todetermine the prevailing torque being applied to the drive shaft, asdescribed above with respect to boxes 206 and/or 208.

With reference now to FIG. 4, a plot of torque versus angle 400 recordedby a transducer shows the predetermined prevailing torque evaluationangle range 402. Minimum and maximum prevailing torques 406 and 408,respectively, represent the low and high ends of a prevailing torquerange 410. Trigger torque 404 typically occurs when the parts, e.g.fastener and stack-up, begin to compress together. A predetermined angleoffset 418 is the amount of angle to look back from trigger torque 404to get to the top end of predetermined prevailing torque evaluationangle range 402. A shut-off threshold 412 is represented by a point inbetween a minimum shut-off torque 414 and a maximum shut-off torque 416.Minimum and maximum shut-off torques 414 and 416, respectively, arepredetermined depending on the stack-up and can be adjusted as neededbased on the prevailing torque measurement and/or shut-off threshold412.

The methods and systems of the present disclosure, as described aboveand shown in the drawings, systems and methods for determiningprevailing torque and calibrating torque wrenches with superiorproperties, including more accurate calibration and in-use measurements,resulting in improved tool performance. While the apparatus and methodsof the subject disclosure have been shown and described with referenceto preferred embodiments, those skilled in the art will readilyappreciate that changes and/or modifications may be made thereto withoutdeparting from the spirit and scope of the subject disclosure.

What is claimed is:
 1. A calibration system comprising: a housing; adrive shaft within the housing extending to a connection point on a wallof the housing; a load application apparatus operatively connected tothe drive shaft to apply a force to the drive shaft; and a plurality ofhousing transducers operatively connected to the drive shaft to measureat least one of an in-line torque or a prevailing torque of the driveshaft.
 2. The calibration system as recited in claim 1, furthercomprising a processing unit operatively connected to at least one ofthe plurality of housing transducers to provide a pass/fail output basedon a comparison between the prevailing torque measurement from at leastone of the housing transducers and a prevailing torque measurement froman external tool.
 3. The calibration system as recited in claim 1, aselectively removable tool operatively connected to the connection pointon the wall of the housing to apply a torque to the drive shaft.
 4. Thecalibration system as recited in claim 3, wherein the selectivelyremovable tool includes a tool transducer to determine at least one ofan in-line torque and a prevailing torque being applied to the driveshaft by the selectively removable tool.
 5. The calibration system asrecited in claim 4, wherein the tool transducer is operatively connectedto a processing unit operatively connected to at least one of theplurality of housing transducers, wherein the processing unit provides apass/fail output based on a comparison between the prevailing torquemeasurement from at least one of the plurality of housing transducersand the prevailing torque measurement from the tool transducer.